The computer-aided NC programming is today's routine in the programming of plate working machines and the programming of NC control is carried out by means of a separate computer or terminal, separately from a working machine, said working machine operating normally during the course of programming. The programming of plate working centers and particularly integrated systems (FMS, FMC), wherein a single system includes a plurality of combined working machines performing a variety of operations, employs currently nearly exclusively purpose-designed software systems which facilitate a simple programming of effective manufacturing techniques (multiplication, nesting etc.).
In the latest programming systems, the trend of development has proven to be a combination of computer-aided design and programming by means of a so-called DAD/DAM system, whereby the actual NC programs required for operations are developed on the basis of the geometric data compiled in CAD planing partly during the course of planning or the development thereof can be automated for a relatively easy performance. This type of integrated CAD/CAM system is essentially better than a software package compiled from a plurality of individual programs, since there is no need for the transfer of files between different programs.
A further production developement based on a so-called JOT (just on time) principle and the automatic flexible manufacturing technique, such as FMS (Flexible Manufacturing System) required thereby, which can also be linked with a CAD/CAM system, has led to the fact that the above-described earlier development has primarily been the result of the development of working machines and automatic data processing and the starting point or basis has not been the rationalization according to the real requirements of production and manufacturing. The aim of such JOT-principle based flexible manufacturing system, particularly in plate working technique, is the integration of various plate working operations (punching, bending, shearing, welding etc.) as a single centrally controllable production system. In JOT production, the flexible automated production equipment is used to manufacture products for just a proper purpose (JOT), i.e. just the amount needed for a particular manufacturing batch. The intention is to keep manufacturing batches as small as possible as it is desirable to minimize the capital tied in unfinished production.
This leads to smaller series but, on the other hand, it is necessary to produce even small series as efficiently and economically as large series. This requires an automated passage for data and material. In the production of plate articles, problems are particularly associated with the material handling system on the unloading side of punching and shearing units, since the system should be capable of sorting and stacking pieces arriving rapidly in random order in their own stacks. The system must also be capable of grouping the pieces according to the proper sizes thereof for subsequent working operations by collecting segments made of various plate blanks into groups (e.g. a single pallet for all the segments of a particular article intended for edge trimming etc.).
The cutting or shearing of a plate blank and the handling of plates cut out of it for further production or intermediate storage can be currently carried out by using shearing, conveying, inloading and sorting mechanisms which are programmable and linked with a CAD/CAM system and apply said flexible manufacturing system (FMS). One problem of the current solutions has however proved to be a different momentary operating speed of the above-mentioned mechanisms, whereby the efficiency of the total operation has been determined according to a mechanism having a slower operating speed. A momentary difference in operating speed refers to the fact that, although the mechanisms have nominal operating speeds that are nearly matching, the cutting or shearing of individual plates and the transfer thereof onto a conveyor between mechanisms takes place within a fraction of the time required for removing a corresponding plate from said conveyor. Accordingly, the cutting mechanism requires a setting-up and transitional period for a fresh plate, something that is not required by a continuous-action unloading and handling mechanism.